Thread shearing device



p 21, 1965 I. DELLA BELLA ETAL 3,206,948

THREAD SHEARING DEVICE 2 Sheets-Sheet 1 Filed April 13, 1964 Inventors:ITALO DELLA BELLA BERNHAPD SCHOLZ P 1955 l. DELLA BELLA ETAL 3,206,948

THREAD SHEARING DEVICE 2 Sheets-Sheet 2 Filed April 15, 1964 In ventom ITA LO DELLA BELLA BERNHARD SCHOLZ AGENT United States Patent THREADSHEARING DEVICE Italo Della Bella, Saulheimer Str., and Bernhard Scholz,Gartner Str. 1, both of Worrstadt, Rhineland, Germany Filed Apr. 13,1964, Ser. No. 359,355 Claims priority, application Italy, Apr. 12,1963, 7,678/63 8 Claims. (Cl. 66-145) This application is acontinuation-in-part of our copending application Ser. No. 202,014 filedJune 12, 1962.

Our invention relates to a device for shearing off the loose threads onladies stockings in circular knitting machines with a knife assemblyconsisting of, for example, a pair of knives each with two cutting edgesand driven by electromagnetic or magnetic means, constituting ahigh-frequency vibrator, the assembly being displaced by means of acamming drum in accordance with the various operating phases required.

Hitherto known devices yielded good results regarding safety andreliability of operation, particularly a uniform and practicallycomplete shearing of the loose threads, but had the disadvantage that ifone or more needles accidentally failed to descend in the region ofoperation of the shearing device during the rotation of the needlecylinder, such needles would inevitably break as they hit the shearingknives thereby often damaging the latter.

It is, therefore, the object of the present invention to provide asafety device adapted to overcome this defect. According to theinvention, the kinematic displacement means of the shearing device areprovided with a spring element, extended into an operative position whenthe system of knives is pushed forward, and with a locking meansmaintaining the system of knives in an operative position as well as thespring element in its extended state. Furthermore there is provided acontact pin positioned in front of the system of knives responding uponcontact with a needle and connected to a device for releasing lockingmeans. The safety device according to the invention respondsinstantaneously as soon as a needle that has become caught in its upperposition reaches the contact pin. The release device, which is connectedwith the contact pin, opens the lock instantaneously and the system ofknives under the urging of the spring element immediately reverts fromthe region of the needle cylinder to its inoperative position Breakingof the needle and damage to the knives are thereby prevented. Anotheradvantage of the safety device according to the invention resides inthat it remains fully effective even when upon changeover to anotheryarn or for some other reason the needle cylinder and the needles of thecircular knitting machine have been changed and the shearing device hadto be readjusted with respect to the needle ring. Furthermore, theinvention makes it possible to keep the system of knives near the needlering so that loose threads can be shorn off very closely.

The invention will now be described more fully with reference to theaccompanying drawing in which:

FIG. 1 is a top perspective view of part of .a circular knitting machinefor ladies stockings where the shearing device according to theinvention is to be disposed;

FIG. 2 is a perspective view of a shearing device with a safety deviceaccording to the invention;

FIG. 3 is a perspective view of the parts of the safety device; and

FIG. 4 is a perspective view similar to part of FIG. 2 showing amodification.

According to the drawing, a shearing device comprises a support 1 fixedto a platen 2, or to some other part of the frame of a circular knittingmachine, and whose shearing knives 3 can be adjusted relatively to aneedle cylinder 4 by means of one or more screws 5.

The shearing knives 3 move on a carriage 6 which, in turn, is guided onthe support 1 to move in axial and radial directions to the needlecylinder 4. The carriage 6 is moved by a cable 7 against the action of acompression spring 8 mounted inside the support 1. This spring 8 isextended when the system of knives 3 moves toward the region of theneedle cylinder 4 and is displaced outwardly as the knives 3 moveradially away therefrom. The forward movement of the system of knives 3into the region of the needle cylinder limited by an adjustment screw 9,is carried out as follows:

The cable 7 is covered by a sleeve 10 which resists axial pressure; thecable is connected to the support 1, which is fixed in position, whilethe cable sleeve 10 bears against a socket 12 mounted on an extension 11of the carriage, thereby pushing the knives 3 forward into the region ofthe needle cylinder 4 by way of the carriage 6 and the extension 11thereof.

In accordance with the invention, we provide a safety device for thesystem of knives 3 and the needle cylinder 4 which, on the one hand,causes the system of knives 3 to retract immediately from an operativeto its inoperative position, i.e. out of the region of the needlecylinder 4, when a needle gets caught in the upper position and thuscomes within operating range of the knives 3. On the other hand, thesafety device according to the invention is designed to respond alsowhen the system of knives 3, owing to incorrect adjustment of itsdisplacement over the needle cylinder 4 or the platen 2, has been pushedforward into a region where the needles project at the top. Anelectromagnetic high-frequency vibrator means V is coupled with theblades 3 for relatively displacing same as described in our copendingapplication mentioned above.

The safety device comprises, as a contacting and safety element, acontact pin 13 which projects over or in front of the system of knives3. The contact pin 13 is held with freedom of axial displacement in ablock 14 pivotable at 1411 on the carriage 6. Behind the block 14 aretwo further blocks 15 and 16 clamped to the contact pin 13 by clampingscrews 17. The contact pin 13 is slightly bent at 18 so that it canalways be adjusted in any direction to the correct position with respectto the system of knives 3 by releasing the clamping screws 17 andaxially displacing or rotating the .pin.

A guide pin 19 is fixed in the block 14. This guide pin extends parallelto the rear part of the contact pin 13 and carries a compression spring20 behind the rear clamping block 16 bearing against the rear end of anadjustable socket 21. The two clamping blocks 15 and 16 are slidablymounted on the guide pin 19 so that axial displacement of the contactpin 13 is transmitted to the compression spring 20 through the rearclamping block 16, this spring thereby maintaining the contact pin 13 inits forward position. The tension of the spring 20 can be adjusted bymeans of the socket 21.

The rearward clamping block 16 carries an actuating pin 22 threadinglyengaging the block 16 so as to lie approximately parallel to the contactpin 13. Pin 22 is secured to block 16 by a nut as shown in FIG. 3. Theactuating pin 22 is bent at 24. The position of the actuating pin 22relative to the contact pin 13 can be adjusted as desired by changingthe distance to which it is screwed into the block 16 and/ or byrotation.

The actuating pin 22 acts on a two-armed lever 26 by way of atransmission pin 25. The lever 26 is pivotally mounted at 27 on thecarriage extension 11. The actuating lever 26 supports a locking roller28 located ahead of the front end surface of the socket 12, so as totransmit the thrust exerted on the socket 12 by the cable sleeve 10 tothe carriage extension 11 by way of the actuating lever 26. The socket12 is provided, for this purpose, at its front end with a flange 29; anadditional setting screw 30, fitted to the actuating lever 26, bearsagainst the circumference of this flange to adjust the sensitivityof'response' of the device.

To limit the deflection of the contact pin 13, a stop pin 31 (FIGURE 2)is provided on the support 1 as well as an adjustable abutment 32 on thecarriage 6. The reason for limiting the deflection of the contact pin 13-is to ensure that during operation it will not swing into the region ofthe needle cylinder in which the needles project upwardly, where itmight damage these needles.

During normal operation, to push the system of knives 3 into itsoperative position, the cable or core member 7, which isconnected to thesupport at 1, is pulled at the usual control plate of the machine sothat the sleeve member of the control means exerts a thrust on the rearsurface of the socket 12. This thrust is transmitted to the carriageextension 11 of the blade means by way of the locking roller 28, andfrom there to the carriage 6 and to the system of knives 3. The contactpin 13 participates in this forward displacement; a recess 33 in theblock 16 abuts against the stop pin 31 so that, in the last part of theforward displacement, only the system of knives is pushed forwardly.When the pull on the cable 7 ceases, the spring 8 urges the carriage 6with all the parts connected thereto, as well as the socket 12 and thecable sleeve 10 back into their original position. The main disturbancesin operation that may occur are the following:

(1) By displacement of the support 1 relative to the platen 2, theknives 3 and the contact pin 13 are pushed forwardly into a region ofthe needle cylinder where the needles are raised or in an intermediateposition.

(2) When a needle is damaged, it gets lodged in the upper position, i.e.in the region where the needles are cast off and would then slip intothe knives 3.

In both cases, the safety device according to the. invention operates asfollows:

As soon as the contact pin 13 comes into contact with a needle, thelatter, rotating with the needle cylinder, causes the pin 13 to bedeflected about its axis of swing 14a in the direction of the arrow 34(FIG. 3). The actuating pin 22 of the release means thus presses againstthe transmission pin 25 and deflects the actuating lever 26 of thelocking means so that the locking roller 28 is raised over the flange 29of the socket 12, whereby the lock between the socket 12 and thecarriage extension 11 is re-- leased. The carriage 6 is then free tomove axially relatively to the socket 12 and is pushed back into itsinoperative position by the spring 8. The knives 3 are thereby instantlypulled back from the region of the needle cylinder-4 before any needlecan enter their operating range.

. By this axial displacement of the carriage 6 due to the spring 8, thecarriage extension 11 is pushed into the socket 12. To reverse oreliminate this axial displacement, the cable 7 and its sleeve 10 aredisplaced relatively to each other so that they return to their originalposition, causing the locking roller 28 to run over the rear surface ofthe flange 29 and to become again located ahead of the front surface ofthe flange 29. It is advisable, for this purpose, to chamfer the rearsurface of the flange 29 or at least make it enough so as not to causeany looking effect with respect to the radius of the locking roller 28.The setting of the locking roller 28 in its locking position is mosteasily achieved by keeping the actuating lever 26 constantly under theaction of a spring permanently tending to swing the actuating lever 26in a clockwise-direction, as seen in FIGS. 2 and 3.

To ensure that the locking roller 28 will respond to deflection of thecontact pin 13, it is not necessary to lift the roller 28 completelyover the flange 29, the radius which at that moment lies parallel to thedirection in which the carriage extension 11 and the socket 12 areguided must be lifted over the outer edge of the flange 29 so that theroller can run over the flange. The deflec tion of the actuating lever26 necessary for going beyond this critical position may be very smalland can be adjusted accurately by means of the set-ting screw 30.

In the embodiment described above, the arrangement of the socket 12 ofthe cable 7 and the cable sleeve 10 is provided for a machine control inwhich the cable 7 is constantly under tension as long as the knives 3are operative. It would also be possible to have machine controls beforea pull is exerted on the cable 7 only for a short time only at the.beginning of the, shearing operation and is then immediately released.In such a system of machine control, the sleeve of the cable 7 may bedisposed the socket 12 and bear against the rear end surface of thecarriage extension 11. The socket 12,

like the support 1, is then fixed to an attached part of the machineframe. The roller 28 then' locks the carriage 6 and the system of knives3 in their operative positions, while in the event of any danger'ordisturbance the safety device instantly releases this lock from itsoperative position so that the carriage with the knives 3 can instantlyjump back to the inoperative position. In such a modified construction,however, additional devices would be required to eliminate the lockingof the roller 28 and of the socket 12, 29 at the end of the shearingoperation.

The above example has been described merely as one possible embodimentof the invention. Modifications of details can be visualized, which may,relate to the system of sleeves and sockets to enable the contact pin 13to be moved axially. The arrangement of the spring and the lockingsystem and their construction could also be modified.

What We claim is:

1'. In a shearing device for a circular knitting machine whereby loosethreads are severed from a knit fabric, said device comprising blademeans including at least one pair of relatively reciprocable kniveshaving a pair of cutting edges relatively vibratable for shearing theloose threads upon the introduction thereof between the cutting edges ofsaid knives, and control means operatively coupled with said blade meansfor positioning same in accordance with the operating conditions of theknitting machine, said blade means being displaceable by said controlmeans between an operative position in which said knives. overlie thetips of the lowered needles of the knitting ma-' chine and aninoperative position in which the knives are disposed radially outwardlyfrom said operative position, the improvement which comprises:

spring means stressable upon displacement of said blade means by saidcontrol means into said operative position and urging said blade meansfrom said operative position toward said inoperative position; lockingmeans releasably retaining said blade means in said operative positionagainst the force of said spring means; a contact pin disposed in theregion of said knives and engageable bya needle of the knitting machine;and release means operable by said contact pin for disengaging saidlocking means to permit said spring means to retract said blade meansinto said inoperative position. 2. The improvement defined in claim 1,further comprising a support fixed with respect to the knitting machine,said blade means including a carriage carrying said knives and generallyradially displaceable on said support' relatively to said machine, saidcontrol means including a flexible cable having a sleeve member and acore mem-' said support, said carriage having an axially displaceablesocket co-operating with said locking means.

' 3. The improvement defined in claim 2 wherein said I locking meanscomprises an actuating lever swingably mounted on said carriage betweena locking position wherein said socket is retained against movement withsaid spring means stressed and a release position wherein displacementof said socket is permitted, a restoring spring resiliently retainingsaid lever in said locking position, said socket having a flangeengageable by said lever for retaining said socket, and a locking rollerrotatably mounted on said lever and cammable by said flange upondisplacement of said socket upon the center of rotation of said rollerclearing said flange.

4. The improvement defined in claim 3 wherein said socket is rigid withsaid carriage and said sleeve member is received within said socketwhile being axially displaceable relatively thereto and abuttableagainst said carriage for shifting same, said lever further comprisingan adjusting screw engageable with said flange for regulating thedistance by which said center of rotation of said roller must bedisplaced to clear said flange.

5. The improvement defined in claim 3 wherein said socket is rigid withsaid carriage and said sleeve member is rigid with said socket, saidlever further comprising an adjusting screw engageable With said flangefor regulating the distance by which said center of rotation of saidroller must be displaced to clear said flange.

6. The improvement defined in claim 3 wherein said contact pin isswingable on said carriage and carries an actuating pin forming saidrelease means, said actuating pin bearing against said lever, said leverhaving a transmission pin engageable by said actuating pin, said releasemeans further comprising means for adjusting the position of saidactuating pin relatively to said transmission pin.

7. The improvement defined in claim 6 wherein said contact pin liesgenerally in a horizontal plane and is axially displaceable upon saidcarriage, said carriage being further provided with an adjustabletension spring acting upon said contact pin for resistant axialdisplacement thereof.

8. The improvement defined in claim 2 wherein said contact pin isswingable substantially in a horizontal plane, said blade means furthercomprising adjustable abutment means on said carriage for limiting thedeflection of said contact pin in one sense and a stop pin on saidsupport for limiting deflection of said contact pin in the oppositesense, said stop pin engaging said contact pin for limiting displacementthereof relative to said support with said carriage toward saidoperative position.

References Cited by the Examiner UNITED STATES PATENTS DONALD W. PARKER,Primary Examiner.

1. IN A SHEARING DEVICE FOR A CIRCULAR KNITTING MACHINE WHEREBY LOOSETHREADY ARE SEVERED FROM A KNIT FABRIC, SAID DEVICE COMPRISING BALDEMEANS INCLUDING AT LEAST ONE PAIR OF RELATIVELY RECIPROCABLE KNIVESHAVING A PAIR OF CUTTING EDGES RELATIVELY VIBRATABLE FOR SHEARING THELOOSE THREADS UPON THE INTRODUCTION THEREOF BETWEEN THE CUTTING EDGES OFSAID KNIVES, AND CONTROL MEANS OPERATIVELY COUPLED WITH SAID BLADE MEANSFOR POSITIONING SAME IN ACCORDANCE WITH THE OPERATING CONDITIONS OF THEKNITTING MACHINE, SAID BALDE MEANS BEING DISPLACEABLE BY SAID CONTROLMEANS BETWEEN AN OPERATIVE POSITION IN WHICH SAID KNIVES OVERLIE THETIPS OF THE LOWERED NEEDLES OF THE KNITTING MACHINE AND AN INOPERATIVEPOSITION IN WHICH THE KNIVES ARE DISPOSED RADIALLY OUTWARDLY FROM SAIDOPERATIVE POSITION, THE IMPROVEMENT WHICH COMPRISES: SPRING MEANSSTRESSABLE UPON DISPLACEMENT OF SAID BLADE MEANS BY SAID CONTROL MEANSINTO SAID OPERATIVE POSITION AND URGING SAID BLADE MEANS FROM SAIDOPERATIVE POSITION TOWARD SAID INOPOERATIVE POSITION; LOCKING MEANSRELEASABLY RETAINING SAID BLADE MEANS IN SAID OPERATIVE POSITION AGAINSTTHE FORCE OF SAID SPRING MEANS; A CONTACT PIN DISPOSED IN THE REGION OFSAID KNIVES AND ENGAGEABLE BY A NEEDLE OF THE KNITTING MACHING; ANDRELEASE MEANS OPERABLE BY SAID CONTACT PIN FOR DISENGAGING SAID LOCKINGMEANS TO PERMIT SAID SPRING MEANS TO RETRACT SAID BLADE MEANS INTO SAIDINOPERATIVE POSITION.